6iQ SUMMAEY OF CURRENT RESEARCHES RELATING TO 



insensible. The last parts to move before death are usually the 

 eeconcl or third pair of legs, more usually the third than the second, 

 and the most mobile joint is the last of the tarsus. 



From a few observations which he has made, Canestrini finds that 

 with Myriopoda, as with insects, drought is unfavourable, whilst damp 

 earth promotes the duration of movement. Geophilus shows no signs 

 of inconvenience on being deprived of its head, and many specimens 

 walked vigorously about for some days with the anterior end of the 

 body elevated ; in 10 days all movement had ceased. Scolopendra 

 has considerable vitality if kept in damp earth ; both the body and 

 head have been found to move 8 days after the oj^eration. Julus, 

 under the same conditions, moves its legs, and especially the terminal 

 joints, after 7 days, and the antennfe move for upwards of 48 hours. 



Use of an adhesive substance by Arthropoda in jumping.* — 

 H. Dewitz has already f shown the ajjplication of this principle to 

 walking. But a Cicada in a closed glass tube is able to jump from the 

 bottom on to the cover and from one vertical side to the other, turning 

 in the air ; the contingency of having to jump on to vertical surfaces or 

 the under side of horizontal surfaces, occurs also in nature, viz. in the 

 case of stems and leaves, which are, moreover, smooth, so that claws 

 are ineffectual to support the insect, and sucking-disks would probably 

 not act with sufficient rapidity. Now, the leaping spiders possess a 

 well-developed pedal adhesive apparatus, by the aid of which they 

 can remain attached to the surfaces on which they alight ; the glands 

 which secrete the liquid oi)en all over the balls of the feet, and are 

 especially numerous at their bases. 



a. Insecta. 



Relation of Light to Colour in Evolution of Species. :{: — G. Lewis 

 is disposed to attribute the origin of the colours of insects to the sun's 

 rays rather than to sexual selection. He supposes a process "by 

 which the various rays or wave-movements from the sun impress 

 living organisms with the structure necessary for colour," and terms 

 it " photoplasticity," basing his supposition on the alleged suffi- 

 ciency of this mechanical theory of the action of light to explain the 

 phenomena of colour. After giving many instances from the Insecta 

 of protective coloration, he turns to examples, e.g. Carabus, where the 

 coloration is not protective, and states his belief that the latter are 

 due to the sun's action. 



Constancy and Methodic Habits of Insects in their Visits to 

 Flowers,§ — A. W. Bennett finds that the different classes of insects 

 show very great differences in this respect. Butterflies show but 

 little constancy, except in a few instances ; but they would appear 

 to be guided to a certain extent by a preference for particular colours. 

 The Diptera exhibit greater constancy, though by no means absolute. 



* Zool. Anzeig., vi. (1883) pp. 273-4. 



t See this Journal, ante, p. 303. 



: Trans. Eiitomol. Soc. Lond., 1882, pp. 503-30. 



§ Juurn. Linn. Soc. (Zool.) xvii. (1883) pp. 175-85. 



